The new bicycle drive device is provided which is simple in structure, easy to install, convenient in use, and has a low rate of breakdown. The bicycle drive can begin acceleration without any time delay. The new drive saves human power output and is started with less force.
The utility of bicycles makes them very popular and necessary in both developed or underdeveloped countries. The drive devices of bicycles can be classified into two different kinds, that is, speed-ratio-variable and non-speed-ratio-variable. The latter have a constant ratio of the number of front chain wheel teeth to the rear's, while the former have variable ratios of the number of chain wheel teeth. Both of the two drives have their usage and market positions. However, the structures and power drive characteristics of the two types of drives are similar, that is, with one or many rear chain wheels connected to the rear wheel by a single directional rotation bearing, the human force could be transferred from the front chain wheel to the rear one via the linking chain and the rear wheel can idly rotate while no forces are applied. It is known that after a bicycle is slipping freely with no forces added, there would be a period of time which would pass before the rider could apply power to the bicycles effectively. The effect is caused by the fact that it is only when the rotational speed of the rear chain wheel is higher than that of the rear wheel's, that human power could be transferred to the rear wheel. This effect tends to be more obvious at higher speed, where there is not only a delay before acceleration regained, but also a higher expenditure of human power. To overcome the reaction caused by the slower rotate speed of the rear chain wheel compared to that of the rear wheel, more human power is required. The condition would be more severe when changing from a low speed ratio to a high speed ratio.
For the reasons listed above, it seems that there is still room for improvement in the design of bicycle drive systems.